We plan to focus on the characterization of monoclonal antibodies to Ig allotype and isotype. We will be particularly interested in using these antibodies to examine the differences between cell surface and secreted IgG. We also plan to complete studies defining the cell surface markers on the various stages in the B cell memory development pathway and the relationship between the presence of these markers and the affinity maturation of the immune response. This will involve on the one hand cell separation and transfer studies and on the other the development of methods for more closely analyzing the heterogeneity of the antibody response. In particular, we will use 2-D gel analysis to investigate the breadth of the spectrum of Ig heavy chains produced in low-affinity and high-affinity antibody responses or produced in animals that are partially suppressed for isotype or allotype production.